This is the case of a 66 y.o. RHD M referred for EDX evaluation of progressive right hand weakness over the last two years. He endorses h/o neck stiffness, right shoulder pain radiating to upper arm and more recent numbness along medial aspect right forearm. The patient denies similar symptoms in his left arm/hand or feet. He has no h/o DM, autoimmune disease or cancer. Interestingly, he reports family history of CIDP in his biological brother (confirmed by patient correspondence) and father (deceased).
Physical Examination: significant atrophy right thenar eminence with more mild atrophy right FDI. Mild right distal forearm atrophy compared to asymptomatic left side. Hoffman's neg. DTR's: depressed biceps bilaterally; 1+ triceps and brachioradialis reflexes. MMT: 5/5 B/L DELT/BICEPS/Triceps/Wrist Ext; 4/5 R FDI; 2/5 R APB. Sensation: grossly no decrement to PP between right and left hands.
First EDX Study (2024): do not have full access to
Second EDX Study (Feb 2025):
(1) minimally prolonged DL, very low amplitude & normal CV right median motor evoked response
(2) normal left median and ulnar motor evoked responses
(3) normal right ulnar motor evoked response at ADM & FDI
(4) normal PL, minimally low amplitude and normal CV b/l median SNAPs
(5) normal PL, low amplitude and normal CV right ulnar SNAP
(6) normal DL, minimally lower amplitude and normal CV right radial SNAP
(7) normal PL, low amplitude and minimal CV slowing left ulnar SNAP
(8) normal left radial SNAP
(9) normal bilateral MABC SNAPs
(10) abnormal right mid palm (lumbrical - interossei) study
(11) chronic denervation & reinnervation in all right upper limb muscles worse in C7-8-T1 muscles and active denervatiobn right APB
IMPRESSION:
(1) very severe chronic axonal right median neuropathy distal to branch of FCR
(2) bilateral mild axonal non localizable ulnar neuropathies
(3) chronic mild right C6-7 radiculopathies
(4) chronic severe right C8-T1 radiculopathies
No EDX evidence of right brachial plexopathy. MD made note of the possibility of a remote brachial plexopathy as evidence by the severe denervation and reinnervation of muscles innervated by AIN and prior EDX absence of MABC SNAP.
My EDX Study (Jan 2026) - one moment please :)
I had the benefit of reviewing the following studies:
MRI Right Brachial Plexus: normal
MRI C-spine: small focus myelomalacia C4; mild to moderate spinal canal stenosis C3-7; severe bilateral NF narrowing C3-7
MRI Right Forearm: mild edema within FDP & PQ muscles
Now, my EDX study ...
(1) Right median CAMP - still very low amplitude 1.2 mV and minimal CV slowing forearm
(2) Right ulnar SNAP - NOW ABSENT !!!
(3) Right radial SNAP - NORMAL OL/PL/CV
(4) Right median SNAP D2 - NORMAL OL/PL/CV (no segmental slowing across wrist)
(5) Right median SNAP D1 - NORMAL OL/PL/CV (minimal slowing across wrist)
(6) Right LABC SNAP - NORMAL
(7) Right ulnar CMAP - no interval change in DMLs or amplitudes but now 18 m/s slow across elbow (ADM) and 13 m/s slow across elbow (FDI)
(8) Right ulnar F-waves - proloned latency 33 ms
(9) Persistent active denervation in APB w/ PSWs & CRDs; moderate-to-severe reduced recruitment in APB & FPL muscles (MUPs firing 30 - 35 Hz); less pronounced reduced recruitment in FDI and PT muscles but with sigificant polyphasia and increased duration; deltoid still showed slightly decreased recruitment but no significant polyphasia (above what we would normally expect to see); biceps, triceps and EIP muscles normal recruitment and MUAPs; cervical paraspinal muscles negative
Unfortunately, I did not have time to study patient's contralateral limb.
My EDX Impression: EDX study highly suspicious for a chronic lower trunk and medial cord brachial plexopathy with interval development of mild, demyelinating, motor, ulnar mononeuropathy across the right elbow.
My conundrums ...
(1) When I see persistently low amplitude median nerve CMAPs + absent ulnar SNAPs I usually conclude lower trunk brachial plexopathy but AIN mononeuropathy seems valid here given the markedly decreased recruitment in FPL and PQ muscles and atrophy of thenar eminence and distal volar forearm muscles on clinical examination. Can we see such such atrophy in lower trunk BP lesions? The patient also had FDI weakness but with less demonstrable atrophy (perhaps from the new UNE ?)
(2) The non-localizable ulnar sensory axonal neuropathies ... could they be a precursor to UNE w/ subsequent development of segmental slowing (ie, neuropraxia) of motor fibers across the elbow?
(3) Chronic cervical radiculopathies with absence of on-going denervation and reliance on MUAP analysis ... i know enough that we need to group these neurogenic changes in myotomal distributions but relatively new finding of modestly decreased recruitment in PT muscle can be seen in medial cord BP lesions ???
(4) NMUS Examination - I tracked patient's MN from CT inlet to level of PT. I'm good but not an US guru by any means :) CSA MN at CT inlet 10 mm2 (wnl) -> CSA MN at PQ 13 mm2 (relatively normal as we expect CSA to slightly increase as we scan proximally) -> PQ muscle definitively hyperechoic and atrophied -> it was hard to appreciate the take off the AIN from trunk of MN.
Do you think I should make an amendment to my report ???
Thank you all !
Todd R. Lefkowitz, DO, DABPMR, DABEM, CAQSM
